Water reverse osmosis system and process, and maintenance

Abstract

The present invention relates to a reverse osmosis water device (1), comprising a circuit supplied from an inlet (2) to an outlet (3) located at a downstream portion of said circuit, a pressurization zone (4) connected to said inlet (2), a downstream filtration zone (6) provided with at least two semi-permeable membranes (60), delivering filtered water, and connected downstream of said filtration zone (6), an unfiltered water discharge outlet (9), with a discharge valve (9a) having a perforated wall, so as to, in the closed position of said discharge valve (90), on the one hand, ensure continuous water circulation through said discharge outlet (9), and on the other hand, maintain a minimum pressure within said circuit. The invention also relates to a corresponding reverse osmosis process and a method for maintaining said reverse osmosis device. Figure for the summary: Fig. 2

Description

Title of the invention: Device and method for reverse osmosis of water, and maintenance. Technical field of the invention

[0001] The present invention falls within the field of fluid treatment and water purification by filtration, in particular by reverse osmosis.

[0002] Osmosis, as is known, consists of filtering a dilute solution, called a hypotonic solution, through at least one semi-permeable membrane to obtain a concentrated solution, called a hypertonic solution. In the case of water filtration from a supply network, reverse osmosis makes it possible to obtain purified water, called "osmosis water," downstream of the membrane, with an extremely low concentration of residual particles.

[0003] It should be noted that such a concentration of particles is expressed in "ppm" for "parts per million"; 1 ppm is equivalent to one particle in a million. For the purposes of the invention, the unit of measurement "ppm" is understood generically and also includes the volume fraction, namely "parts per million by volume" (ppmv).

[0004] Typically, the use of reverse osmosis water is useful for many industrial and professional applications, as well as for domestic applications. In particular, due to its very low content of residual particles, especially limescale molecules, osmosis water is often used for cleaning and rinsing the bodies of transport vehicles and in the automotive sector, the superstructures and hulls of boats in the maritime sector, but also glass walls and metal and painted structures in the building sector, or even solar energy conversion panels, such as photovoltaic panels. State of the art

[0005] Currently, reverse osmosis of water is carried out by a dedicated device with a circuit supplied with water at an inlet, for example from a domestic or industrial water supply network. The water is circulated under the pressure of said network upstream to pressurization means, in the form of one or more pumps, delivering an adjustable pressure downstream. Furthermore, the pressurized water passes successively through several filtration zones before reaching an outlet, delivering reverse osmosis water. A main filtration zone comprises one or more semi-permeable membranes, mounted in series or parallel. Passing through each membrane allows the water to be filtered of its impurities. particles. The filtered water is then sent to a downstream portion of the circuit, up to the outlet, where the filtered water can be used. The circuit may also include a pre-filtration zone at the inlet equipped with suitable filtration media, for example with compositions based on salts, activated carbon, or sediments. Each type of these composition filters specific particles, such as impurities or ions.

[0006] The circuit further includes a discharge zone with an outlet for the hypertonic solution laden with particles. This outlet, normally closed during filtration, is opened during membrane maintenance in order to purge the unfiltered water when its particle concentration becomes too high. To do this, the circuit is bypassed, closing the downstream portion of said circuit and redirecting the water flow towards said drain outlet.

[0007] In addition, the circuit can be equipped with various hydraulic components at different specific locations, such as solenoid valves and valves, including a check valve, a pressure gauge or a pressure switch.

[0008] One problem with known reverse osmosis systems lies in the maintenance and upkeep of the membranes in the filtration zone. Indeed, during filtration, the pores that give the membranes their semi-permeable nature become clogged, notably by scale buildup. It is then necessary to circulate a washing solution, or even replace the membranes. This maintenance is tedious and time-consuming. Description of the invention

[0009] The invention aims to overcome the drawbacks of the prior art by proposing a reverse osmosis water device which provides for the continuous removal of a portion of the water laden with particles before filtration by the membranes, which makes it possible to limit the obstruction of their pores and to space out maintenance operations, also increasing the lifespan of the filtration membranes and spacing out their replacement accordingly. Moreover, with part of the hypertonic solution constantly evacuated, by adding residual ion-exchange resin filtration before the outlet, the filtered water then has a lower particle content, found to be less than 1 ppm.

[0010] According to a first aspect of the invention, the water reverse osmosis device comprises - a circuit extending from at least one inlet to at least one outlet located at the level of a downstream portion of said circuit, said circuit being supplied at the inlet by a source of water supply to be filtered; And along said route: - a pressurization zone connected to said inlet through an upstream portion of said circuit; - a filtration zone connected downstream to said pressurization zone, said filtration zone being provided with at least two semi-permeable membranes, delivering filtered water to the downstream portion of said circuit; - connected downstream of said filtration zone, an unfiltered water discharge outlet, equipped with a discharge valve, said discharge valve comprising a body within which a circulation channel connects the upstream and downstream of said valve and being equipped with a movable element between an open position and a closed position in blocking said circulation channel and discharge outlet. Advantageously, such a reverse osmosis device is characterized in that - said discharge valve includes a perforated wall, so as to, in the closed position of said discharge valve, on the one hand, ensure continuous circulation of water along said channel and through said discharge outlet, and on the other hand, maintain a minimum pressure within said circuit.

[0011] According to additional, non-limiting features:

[0012] - said perforated wall is the perforated organ with through orifices; and / or - preferably, said perforated wall is an internal edge of said body located between upstream and downstream on either side of said organ, said internal edge being perforated with through orifices. According to one embodiment, said evacuation valve is a solenoid valve type valve, with said organ formed by a piston mounted to slide inside the body between the open and closed positions.

[0013] According to one embodiment, each of the orifices has a diameter between 1.2 and 3.5 millimeters.

[0014] According to one embodiment, said filtration zone comprises two membranes mounted in series and each of the orifices has a diameter of 1.2 millimeters.

[0015] According to one embodiment, said filtration zone comprises three membranes mounted in series and each of the orifices has a diameter of 1.5 millimeters.

[0016] According to one embodiment, said reverse osmosis device includes along the downstream portion, before said outlet, residual filtration means based on ionic resin.

[0017] According to a second aspect, the invention also relates to a method for maintaining the reverse osmosis device according to the first aspect, said method consisting of that a cleaning of the membranes is carried out by circulating along said circuit an aqueous washing solution based on vinegar, preferably with a concentration of about 20 to 30% vinegar.

[0018] According to a third aspect, the invention relates to a reverse osmosis process for water. Preferably, such a reverse osmosis process is provided for the implementation of the reverse osmosis device according to the invention.

[0019] In particular, the reverse osmosis process for water comprises at least the following steps: - water is supplied to be filtered to a circuit at the level of an inlet; - the water is pressurized within said circuit; - water is filtered under pressure by passing it through at least two semi-permeable membranes; - the filtered water is circulated along a downstream portion of said circuit until it reaches an outlet; characterized in that - a quantity of water is removed and filtered continuously during the filtration process.

[0020] According to one non-limiting embodiment, said reverse osmosis process is characterized in that - the said quantity of water is evacuated through an evacuation outlet equipped with a valve in the closed position, blocking said evacuation outlet, said valve being equipped with a perforated wall between the upstream and downstream sides; and in that - said wall is perforated in a specific way, depending at least on the pressure within said circuit and / or the number of said at least two membranes. Presentation of the drawings

[0021] Other features and advantages of the invention will become apparent from the following detailed description of non-limiting embodiments of the invention, with reference to the accompanying figures, in which:

[0022] [Fig.1] schematically represents a view of the architecture of an embodiment of the reverse osmosis device equipped with two filtration membranes, showing in particular the circulation of water along the circuit;

[0023] [Fig.2] schematically represents a cross-sectional view of a mode of realization of a valve equipping the reverse osmosis device, with a circulation channel between an inlet and an outlet sealed by a sealing membrane in the closed position, showing in particular a valve body perforated with through orifices connecting the inlet and the outlet;

[0024] [Fig.3] schematically represents a view similar to [Fig.2], with the membrane in the open position, ensuring traffic flow along said canal; and

[0025] [Fig.4] schematically represents a view of the architecture of a mode of construction of the reverse osmosis device equipped with a washing solution tank during the maintenance of said device and the cleaning of the membranes, showing in particular the circulation of this washing solution along the circuit. Detailed description

[0026] According to a first aspect, the invention relates to a reverse osmosis device 1, or "device 1", intended to ensure the filtration of water by a reverse osmosis process.

[0027] To do this, the device 1 first includes a circuit extending from at least one input 2 to at least one output 3 located at a downstream portion of said circuit.

[0028] Furthermore, said circuit is supplied at its inlet by a source of water to be filtered, namely a domestic or industrial type supply network. The circulation of water along the circuit, in particular along an upstream portion from inlet 2, therefore takes place at least partly under the pressure of said supply network. It should be noted that the circuit may be equipped with a hydraulic device at inlet 2, limiting the return flow to the water supply. Such a device may, in particular, be an inlet solenoid valve 20. This inlet solenoid valve 20 is controlled to be open when device 1 is switched on and during its use, and is closed when not in use or when device 1 is switched off, thus cutting off the water supply circuit. Furthermore, device 1 includes, along said circuit, a pressurization zone 4 (or zone 4) connected to said inlet 3 via an upstream portion of said circuit. This zone 4 allows for pressure increase to deliver a higher pressure to outlet 4, depending on the desired application, as well as for the filtration performed downstream. This pressure increase downstream of the circuit also maintains sufficient pressure to ensure evacuation, as will be seen later.

[0029] According to one embodiment, the pressurization zone 4 may include several different types of hydraulic components. In particular, along a main portion of the circuit from the inlet 4, zone 4 includes at least one pump 40. This pump 40 may be of any type, electrically powered, in order to increase the pressure downstream of the circuit. In particular, the pump 40 is adapted to provide a pressure between 180 psi and 210 psi, preferably in the order of 200 psi. Note that 1 psi (for "pound per square inch") is equivalent to approximately 6894.76 Pa (Pascal), or approximately 0.0689476 bar.

[0030] In addition, the pressurization zone 4 may include a bypass 5 in the form of a branch connecting the downstream and upstream of said pump 40. Such a bypass 5 allows recirculation of water, in particular in the event of blockage downstream, especially during the commissioning and use of the device 1, serving as a safety measure against possible overpressure within the circuit, also limiting the risks of water hammer. Further on, said bypass 5 may include an adjustable throttling valve, in particular of the throttling valve type 50. This valve 50 allows the pressure to be regulated, preferably manually, until a minimum threshold pressure is reached for the downstream filtration, as well as for the outlet application 3.

[0031] In addition, the filtration zone 4 may also include a hydraulic pressure measuring device, connected to the circuit downstream of said pump 40. In particular, zone 4 includes a pressure gauge 41 located downstream of the pump 40.

[0032] Once the overpressure has been achieved through zone 4, the device 1 provides for filtration and includes, for this purpose, a filtration zone 6 connected downstream to said pressurization zone 4. The said filtration zone 6 is provided with at least two semi-permeable membranes 60, delivering filtered water to the downstream portion of said circuit.

[0033] According to one embodiment, the filtration zone 6 is provided with three membranes 60.

[0034] It should be noted that the membranes 60 can be mounted in parallel, but preferably in series, with the water circulating successively through each of the membranes 60.

[0035] Further on, the membranes 60 can be of any type, preferably so-called "low pressure" membranes, ensuring filtration from a pressure of at least 10 to 20 psi, but also up to high pressures of the order of 500 to 600 psi, or higher, allowing to obtain suitable filtration for lower energy consumption (i.e. of the pump 40). Membranes 60 can be made of any type of material with suitable permeability, in particular in the form of a composite film, especially polyamide, preferably aromatic polyamide.

[0036] In order to improve filtration, according to one embodiment, between the inlet 3 and the pressurization zone 4, a pre-filtration zone 7, equipped with pre-filtration means 70 at least based on activated carbon. Preferably, the pre-filtration means 70 comprise several successive filters 71, based on activated carbon, sediments and / or in the form of Ion resins. Such filters 71 provide pre-filtration of particles of various sizes, preferably larger than 5 microns (or micrometers, equivalent to one millionth of a meter). Such filters 71 can also filter specific particles, particularly organic ones such as bacteria, or certain chemical compounds, such as chlorine-based compounds or certain mineral salts. These filters 71 can then be used as water softeners or for desalination of incoming water 2. Furthermore, said inlet solenoid valve 20 is located at said pre-filtration zone 7 upstream of pre-filtration means 70.

[0037] According to one embodiment, the reverse osmosis device 1 comprises, along the downstream portion of the circuit, before said outlet 3, residual filtration means 8. These residual filtration means 8 can be of any type, preferably based on ionic resin. After filtration through the membranes 60, the residual filtration means 8 produce water with a concentration of less than 1 ppm. This residual filtration thus results in final filtration at outlet 3, reducing the particle removal rate from 95% to 100%, thus avoiding any residue, even minimal.

[0038] It should be noted that the circuit may include other hydraulic components to control the circulation within the circuit, in particular towards outlet 3. For example, as seen in Figures 1 and 4, a non-return valve 30 can be positioned with outlet 3, preferably before the residual filtration means 8, preventing a return to the membranes 60 of the filtration zone 6. For example, a pressure switch 31 can be mounted between the filtration zone 6 and the outlet 3, preferably between the non-return valve 30 and the filtration means 8. Such a pressure switch 31 monitors and regulates the pressure within this part of the circuit, ensuring a suitable pressure depending on the application and use of the device 1. This pressure switch 31 can be connected to the pump 40, particularly via suitable control means, to control its start-up or shutdown, or even its operating level, depending on the pressure measured before the outlet 3 of the circuit. This pressure switch 31 is particularly useful for regulating pressure fluctuations resulting from continuous drainage, as will be seen later.

[0039] Further on, the device 1 includes, connected downstream of said filtration zone 6, an outlet 9 for the discharge of unfiltered water. Such an outlet 9 allows the circuit to be purged, in particular of particle-laden solutions obtained upstream of the membranes 60. Advantageously, the invention provides for a permanent evacuation during the operation of the device 1. In other words, during filtration through the membranes 60, a quantity of water laden with particles is constantly evacuated at the level of said evacuation outlet 9. To achieve this, the unfiltered water outlet 9 is equipped with a specific discharge valve 90. Such a discharge valve 90 comprises a body 91 within which a circulation channel 92 connects the upstream and downstream sides of said valve 90. In addition, the valve 90 is equipped with a movable element 93 between an open position and a closed position, blocking said circulation channel 92 and the discharge outlet 9. In particular, said discharge valve 90 includes a perforated wall, so as to ensure, in the closed position of said discharge valve 90, on the one hand, the continuous circulation of water along said channel 92 and through said discharge outlet 9, and on the other hand, to maintain a minimum pressure within said circuit. In other words, in the closed position of valve 90, under the effect of the pressure within the circuit, a perforated wall of the discharge valve 90 allows a quantity of water to pass from upstream to the discharge outlet 9. In short, the discharge valve 90 is perforated. According to one embodiment, said perforated wall is the element 93 perforated with through orifices 94. For example, the element 93 may be a valve in which said orifices 94 are provided. According to another preferred embodiment, said perforated wall is an internal edge 95 of said body 91 situated between the upstream and downstream on either side of said organ 93, said internal edge being perforated with through orifices 94. These two embodiments can be combined, with an organ 93 and an internal edge 95 provided with through orifices 94. Figures 3 and 4 show an example of an embodiment of a valve 90 with a body 91 having an internal edge 95 through which the orifices 94 provided are traversing between one and the other of the sides of said internal edge 95.

[0040] According to one embodiment, said valve 90 is a solenoid valve, with said element 93 formed by a piston 96 mounted to slide within the valve body 91 between the open and closed positions. [Fig. 2] shows the piston 96 in the closed position, blocking the circulation channel 92, while [Fig. 3] shows the piston 96 in the open position of the circulation channel 92.

[0041] Furthermore, each of the orifices 94 can have a diameter between 1.2 and 3.5 millimeters (1 mm = 1 / 1000th of a meter). This sizing allows a specific quantity of large particles to pass through, without passing through the membranes. In particular, it has been observed that with orifices 94 smaller than 1.2 mm, continuous drainage leads to fouling of the membranes 60, while with orifices larger than 3.5 mm, the pressure within the circuit drops drastically, limiting the intended use and overloading the pump.

[0042] Furthermore, the orifices 94 can be of any shape and type, preferably in the form of a circular cross-section, namely round holes, made through the material of said wall to make it perforated. In addition, the number and dimensions of the orifices 94, as well as their distribution on the perforated wall, namely the element 93 or the internal edge 95, depend on the pressure to be maintained within the circuit, as well as on the characteristics of said valve 90, in particular its element 93 or its internal edge 95.

[0043] The sizing of the orifices 94 also depends on the number of membranes 60 in the filtration zone 6. Thus, according to one embodiment, said filtration zone 6 comprises two membranes 60 mounted in series. Consequently, each of the orifices 94 has a diameter of 1.2 millimeters. According to another embodiment, said filtration zone 6 comprises three membranes 60 mounted in series. Consequently, each of the orifices 94 has a diameter of 1.5 millimeters.

[0044] According to another aspect, the invention relates to a reverse osmosis process for water. Such a process can be particularly designed for the implementation of the reverse osmosis device 1.

[0045] The reverse osmosis process includes at least the following steps. First, water to be filtered is supplied to a circuit at the level of an inlet 2. This supply is carried out in particular by a supply network, as mentioned above.

[0046] The supplied water is pressurized within said circuit. Such pressurization can be carried out through the pressurization zone 4, as mentioned above. In addition, the water is filtered under pressure by passing through at least two semi-permeable membranes. After filtration, the filtered water is circulated along a downstream portion of said circuit to an outlet 3. Other filtrations can be considered, such as pre-filtration at inlet 2 and / or residual filtration at outlet 3, as mentioned above. Advantageously, the reverse osmosis process involves the continuous removal of a quantity of water to be filtered during the filtration process. In other words, the water laden with particles is constantly removed during operation, reducing particle aggregation within the membranes and limiting their fouling, thus maintaining filtration quality during use.

[0047] According to one embodiment, said quantity of water is discharged through a discharge outlet 9 equipped with a valve 90 in the closed position, thus blocking said outlet 9 for evacuation. To achieve this, said valve 90 is equipped with a perforated wall between the upstream and downstream sides. Furthermore, said wall is perforated in a specific way, depending at least on the pressure within said circuit and / or the number of said at least two membranes 60. In particular, as mentioned previously, the wall is perforated by means of through orifices 94 with a specific dimensioning, as mentioned above.

[0048] According to a subsidiary embodiment, during the reverse osmosis process, the inlet water 2 of the circuit can be heated to improve filtration. Indeed, with warm water, on the order of 25 to 35°C (degrees Celsius), the materials of the semi-permeable membranes 60 expand, improving water transfer while reducing particle transfer, and limiting fouling of said membranes 60. Furthermore, in the corresponding embodiment, the reverse osmosis device 1 is then equipped, at inlet 2, with a preheating means, for example in the form of an instantaneous water heater, in particular of the electric type. In particular, downstream temperature measurement devices can be installed along the circuit to verify heating at a defined and adjustable setpoint temperature. These measurement devices can, notably, control a closed circulation via bypass 5 until the setpoint temperature is reached, and then open the circuit to redirect the heated water to the filtration system.

[0049] According to another aspect, the invention also relates to a method of maintaining a reverse osmosis water device 1 according to the first aspect. Such a maintenance procedure involves cleaning the membranes 60 by circulating along said circuit an aqueous washing solution based on vinegar, preferably with a concentration of about 20 to 30% vinegar, in particular 30% vinegar plus or minus 5%. In addition, during maintenance, the drain valve 9 can be controlled to open, in order to purge the circuit.

[0050] In particular, as shown in [Fig. 4], said circuit can then be equipped with a reservoir 10 connected to said circuit and containing said washing solution. Such a reservoir 10 is connected downstream of the inlet 2, preferably downstream of the pre-filtration zone 7, in particular at the bypass 5 of the pressurization zone 4. Furthermore, such washing can be carried out at low pressure, ensuring that the washing solution is redirected to the discharge outlet 9, not passing through the residual filtration means 8, due to the presence of the non-return valve 30 and the pressure switch 31. In addition, a bypass in the form of a shunt 100 can be placed along the circuit, after the outlet of the filtration zone 6 and the membranes 60 and before said non-return valve 30, sending the flow back to the discharge outlet 9. Furthermore, said discharge outlet 9 can be connected to said tank 10, in order to circulate said washing solution. In short, the cleaning is carried out in a closed circuit. In addition, it is possible to soak the circuit by circulating the washing solution for a given period, in particular on the order of several tens of minutes, for example 15 to 20 minutes, then cutting off the circulation for a determined period, in particular several hours, for example on the order of 8 to 10 hours. Next, we disconnect reservoir 10, then we flush the circuit for a set period of time, in particular a few minutes or tens of minutes. Thus, the washing solution ensures regular maintenance, extending the lifespan of the 60 membranes, as well as other circuit components.

Claims

Demands

1. A reverse osmosis water device (1), comprising - a circuit extending from at least one inlet (2) to at least one outlet (3) located at a downstream portion of said circuit, said circuit being supplied at the inlet (2) by a source of water to be filtered; and along said circuit: - a pressurization zone (4) connected to said inlet (2) through an upstream portion of said circuit; - a filtration zone (6) connected downstream to said pressurization zone (4), said filtration zone (6) being provided with at least two semi-permeable membranes (60), delivering filtered water to the downstream portion of said circuit;- connected downstream of said filtration zone (6), an unfiltered water outlet (9), equipped with a discharge valve (90), said discharge valve (90) comprising a body (91) within which a circulation channel (92) connects the upstream and downstream of said valve (90) and being equipped with a movable element (93) between an open position and a closed position in blocking said circulation channel (92) and the discharge outlet (9); characterized in that - said discharge valve (90) comprises a perforated wall, so as, in the closed position of said discharge valve (90), on the one hand, to ensure continuous water circulation along said channel (92) and through said discharge outlet (9), and on the other hand, to maintain a minimum pressure within said circuit.;

2. Reverse osmosis device (1) according to the preceding claim, characterized in that - said perforated wall is the organ (93) perforated with through orifices (94); and / or - said perforated wall is an internal edge (95) of said body (31) located between the upstream and downstream on either side of said organ (93), said internal edge (95) being perforated with through orifices (94).

3. A reverse osmosis device (1) according to any one of the preceding claims, characterized in that - said discharge valve (90) is a solenoid valve type valve, with said organ (93) formed by a piston (96) mounted to slide inside the body (91) between the open and closed positions.

4. Reverse osmosis device (1) according to any one of claims 2 to 3, characterized in that - each of the orifices (94) has a diameter between 1.2 and 3.5 millimeters.

5. Reverse osmosis device (1) according to any one of claims 2 to 4, characterized in that - said filtration zone (6) comprises two membranes (60) mounted in series; and in that - each of the orifices (94) has a diameter of 1.2 millimeters.

6. Reverse osmosis device (1) according to any one of claims 2 to 4, characterized in that: - said filtration zone (6) comprises three membranes (60) mounted in series; and in that - each of the orifices (94) has a diameter of 1.5 millimeters.

7. Reverse osmosis device (1) according to any one of the preceding claims, characterized in that it comprises: - along the downstream portion, before said outlet (3), residual filtration means (8) based on ionic resin.

8. A method for maintaining a reverse osmosis water device (1) according to any one of the preceding claims, wherein - the membranes (60) are cleaned by circulating along said circuit an aqueous washing solution based on vinegar, preferably with a concentration of about 20 to 30% vinegar.

9. A reverse osmosis process for water, comprising at least the following steps: - water to be filtered is supplied to a circuit at an inlet (2); - the water is pressurized within said circuit; - the pressurized water is filtered by passing through at least two semi-permeable membranes (60); - the filtered water is circulated along a downstream portion of said circuit to an outlet (3); characterized in that - a quantity of water to be filtered is constantly removed during the filtration process.

10. Reverse osmosis process according to the preceding claim, characterized in that - said quantity of water is discharged through an outlet (9) equipped with a valve (90) in the closed position, blocking said outlet (9), said valve (90) being equipped with a perforated wall between the upstream and downstream sides; and in that - said wall is perforated in a specific way, depending at least on the pressure within said circuit and / or the number of said at least two membranes (60).

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